Piston Install Valve relief orientation
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Piston Install Valve relief orientation
I did some searching on the forum but I did not find anything that addresses this problem. I purchased this engine from a friend who cannot afford to finish the build and because it it is perfect for my 1968 C3. Came with new pistons, but not sure how to orient the rods and the valve reliefs to make sure they are in correctly. Any helpful suggestions for getting this right appreciated. BTW. No marks on pistons indicating which side should face front of engine, so at a loss there. However, the machine shop did label the pistons so I'm hoping that might mean something.
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The *589* side of the piston goes toward the lifter valley. It appears that the valve notches are the same.
Do all pistons have same part number?
On some pistons the intake and exhaust notches are different and you have to be careful. If you look at the intake/exhaust valve order you'll see that with the two exhaust valves side by side on the center cylinders and those type pistons would need to be inserted to get the smaller notch placed with the exhaust valves and larger with intakes. You see this on many flat top style pistons.
The rods are placed on the pistons with the *large chamfer* side of big end/rod bearing facing the outside of the rod journal (facing the mains). Another indicator is that the bearing tangs should usually be placed away from the cam.
JIM
Do all pistons have same part number?
On some pistons the intake and exhaust notches are different and you have to be careful. If you look at the intake/exhaust valve order you'll see that with the two exhaust valves side by side on the center cylinders and those type pistons would need to be inserted to get the smaller notch placed with the exhaust valves and larger with intakes. You see this on many flat top style pistons.
The rods are placed on the pistons with the *large chamfer* side of big end/rod bearing facing the outside of the rod journal (facing the mains). Another indicator is that the bearing tangs should usually be placed away from the cam.
JIM
Thread Starter
Intermediate
Joined: Apr 2008
Posts: 28
Likes: 0
The *589* side of the piston goes toward the lifter valley. It appears that the valve notches are the same.
Do all pistons have same part number?
On some pistons the intake and exhaust notches are different and you have to be careful. If you look at the intake/exhaust valve order you'll see that with the two exhaust valves side by side on the center cylinders and those type pistons would need to be inserted to get the smaller notch placed with the exhaust valves and larger with intakes. You see this on many flat top style pistons.
The rods are placed on the pistons with the *large chamfer* side of big end/rod bearing facing the outside of the rod journal (facing the mains). Another indicator is that the bearing tangs should usually be placed away from the cam.
JIM
Do all pistons have same part number?
On some pistons the intake and exhaust notches are different and you have to be careful. If you look at the intake/exhaust valve order you'll see that with the two exhaust valves side by side on the center cylinders and those type pistons would need to be inserted to get the smaller notch placed with the exhaust valves and larger with intakes. You see this on many flat top style pistons.
The rods are placed on the pistons with the *large chamfer* side of big end/rod bearing facing the outside of the rod journal (facing the mains). Another indicator is that the bearing tangs should usually be placed away from the cam.
JIM
All part numbers are the same. There appears to be Two tabs and this appears to be the larger side of the chamfers. As shown here. Correct?
Now what's interesting is that the number 1 and 2 rods appear to be backwards in relation to the other rods. Is this normal?
Here is a picture of Rod 6.
Race Director
Joined: Jan 2000
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From: Corsicana, Tx
2020 C2 of the Year - Modified Winner
2020 Corvette of the Year (performance mods)
C2 of Year Winner (performance mods) 2019
2017 C2 of Year Finalist
Can't really tell #1 and #2 in that pic..but the ones with the arrows are correct as long as the pistons are pointing the right way.
JIM
JIM
Thread Starter
Intermediate
Joined: Apr 2008
Posts: 28
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Should the valve relief always be toward the lifter valley or is the opposite for each side.
2,4,6,8 towards lifter valley
1,3,5,7 away from lifter valley.
I ask because the numbers are written on the other side for odd numbered pistons.
Anyone have a picture of flat top piston engine with only one side of valve reliefs with heads removed? Would surely help. Engine is 68 327. I feel dumb asking this but I am having a hard time visualizing the valves opening and closing and with the proper piston orientation.
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